Unconventional superconductivity originating from disconnected Fermi surfaces in iron pnictides

作者：Kuroki Kazuhiko^*

来源：Physica C-Superconductivity and Its Applications, 2010, 470: S267-S272.

DOI：10.1016/j.physc.2009.11.099

• Iron pnictides
• Disconnected Fermi surface
• Spin fluctuations
• Pairing symmetry
• Lattice structure

For the iron-based high T-c superconductors, we construct a minimal model, where all of the five Fe d bands are involved. Applying a five-band RPA to this model, we find that multiple spin fluctuation modes develop due to the nesting between disconnected Fermi surfaces. The superconductivity originating from the cooperation or competition between these multiple spin fluctuation modes depends on the lattice structure. In particular, the appearance of the Fermi surface around (pi, pi) in the unfolded Brillouin zone is sensitive to the pnictogen height h(pn) measured from the Fe plane, and the height can act as a switch between high T-c nodeless and low T-c nodal pairings. In the high T-c case, the superconducting gap is fully open on all of the five Fermi surfaces, but changes sign across the nesting vectors that bridge the disconnected Fermi surfaces. This is reminiscent of our earlier proposal of realizing high T-c superconductivity in materials with disconnected Fermi surfaces.

• 出版日期2010-12